1. Field of the Invention
The invention relates to apparatus for processing a zigzag folded web of forms into a stack whereat superposed forms are vertically aligned and cut at a given stack location for removal of a stack unit or section. The provided apparatus comprises a table movable in the vertical plane and positioned near the end of a feed conveyor. Vertical confining walls assist in forming forms of said web fed onto said table into a desired vertical stack, and a knife movable substantially in a horizontal plane transversely to the stack cuts a fold between two contiguous forms when a vertical stack is formed on the table.
2. Description of the Prior Art
Such type of apparatus is known from EP-A-O 244 003. In the latter device it is necessary that a knife having a sharp cutting edge be able to penetrate into a form stack to cut off the fold positioned at the far side of the stack or pile. A fold, however, will never define a true straight line. The latter is particularly true when thin papers are used in the formation of the zigzag forms. Also, a form will not lie exactly in one plane. This results in the danger that when the knife is urged into the pile it will not lie exactly between two forms or sheets, but it will also lie partly against folds present between the sheets which lie below and above such sheets. In consequence, desired separation of a shaped form unit on the table from the successive web forms will not take place and interruptions in the working of the apparatus will occur.
Further it should be noted that in U.S. Pat. No. 4,508,527 apparatus is described for bringing a zigzag folded web of forms into the shape of a pile including a horizontally movable knife plate for cutting off the web. To arrange the sheets into a stack or pile, the folds of the pile are guided by spiral rotors rotating around vertical axes. Also, the knife plate is divided into two sections comprising a first section provided with the cutting edge and which is brought into the pile at a high speed and a second section which is moved with a lower speed and will join said first section afterwards.
Such a device will only be suitable for use with a web of forms made paper having a certain stiffness because otherwise the danger is present that the first section of the knife which is moving at a high speed, will come into contact with the web of forms at a wrong location so as to result in form damage and/or work stoppage.
The object of the provided invention is to remove the above-mentioned disadvantages of the prior art. To that end there is provided an apparatus comprising at least one stack-opening finger together with support means for such finger so that it can be moved from a position outside the pile or stack of forms to a position in which it is positioned partly in said pile. The provided finger lifts the stack forms lying above it for forming a slit or opening. A flexible plate is also provided extending substantially in the horizontal plane in association with means for supporting this plate such that it can be moved in the horizontal plane into the knife-formed slit. An adjacent knife plate is positioned below the flexible plate and support means for the knife plate to enable the latter to move with the flexible plate. The cutting edge of the knife plate is positioned at some distance behind the leading edge of said flexible plate until the flexible plate is positioned under substantially the total unit and close to the fold to be cut, and there is brought to a stop. The knife plate is then moved beyond the flexible plate leading edge for cutting the fold.
Thus the apparatus finger first forms a slit between two succeeding forms or a formed stack after which the flexible plate is moved into the slit. The knife plate is positioned below the flexible plate as the flexible plate supports that portion of the web of forms located above it. Thus this stack portion cannot come into contact with the knife plate. As a result, the knife plate only functions for cutting a stack fold and there is no danger that the knife plate will engage other portions of the web forms defining the stack.
In the provided apparatus, the support means for the slit-forming finger may comprise a shaft connected to the finger which in the inoperative position of the finger is substantially vertically disposed. The shaft is associated with means for rotating said shaft to bring said finger into the pile. A support plate is provided on which said shaft is mounted together with means for supporting said support plate in such manner that after the finger is brought into the pile said finger will move substantially in the vertical direction.
The provided finger of the apparatus is able to pivot into the stack of forms in substantially the horizontal plane, and then move upwardly to form the desired slit in the form stack or pile. By pivoting the finger horizontally into the pile, damage of sheets between which the finger has been inserted, will be prevented. Obviously the leading edge of the finger which first contacts the form stack should be thin so that it can penetrate between two succeeding or contiguous sheets.
In addition, hold down means may be present in the provided apparatus which can be brought into the slit formed by the pile-opening finger. The hold down means is adapted to press the pile portion lying below the slit-forming finger downwardly over a given length of the sheets forming the stack.
Because the hold down means need only be brought inwardly into the pile a short distance, the slit made by means of the opening finger will normally be large enough to provide entry of the hold down means. In view of the fact that the flexible plate together with the knife plate can move adjacent to and over the hold down means after the latter is pressed onto the pile, a reliable operation of the provided apparatus is assured. Also, when using thin paper in the formation of the web forms, the flexible plate can be moved into the stack slit when it is horizontally actuated and it will not engage a fold of the form web directed towards or facing the plate.
In practice it has been found that the parts of the web of forms coming to rest on the apparatus table in most cases will not lie flat on the table. When the web of forms is supplied to the device by means of a conveyor belt running at an incline, and this is indicated in the above mentioned European patent application, the edges where the folds are present will lie higher than the middle portion of the related sheet.
To prevent difficulties resulting from such initial non-planar condition in accordance with this invention there is provided in the table at least one strip running parallel to the opposed folds of the web of forms. Such strip during the supplying of the web of forms to the table is positioned at some distance above the upper surface of the table from which it is formed.
Before a fold is cut off for forming a form unit by moving the flexible plate and the knife plate into the slit, as above described, such table strip will be brought downward into a table-receiving recess, simultaneously performing a sheet-aligning function as will hereinafter be described. The table strip will enable the sheets of the web of forms to assume a substantially flat position so that disturbances in the operation of the device will be prevented.
The provided apparatus also includes means for vibrating the stack-supporting table for assisting in desired positioning of the web of forms on the table as will also hereinafter be described in greater detail.
In accordance with a preferred embodiment of the apparatus of this invention one of the vertical walls adjacent the table is divided into an upper and a lower section defining a slot through which the stack-opening finger, the hold down means, the flexible plate and the knife plate may enter the stack of forms.
In the provided apparatus, the second vertical wall, lying opposite the divided wall, can be positioned such that this can be brought into vibration or into a reciprocating movement. It has been found that such movements assist in the formation of a form stack in which the folds will lie exactly above each other in vertical alignment. By such alignment, the dimensions of the pile will be exactly fixed resulting in ease of packaging of the stack segments or units formed by the provided apparatus.
According to a further embodiment of the invention, a conveyor belt can be provided near the upper rim of the second vertical wall, which belt runs substantially horizontally and joins the form feed conveyor whereby the web of forms is supplied to the provided apparatus.
The provided conveyor belt enables the fed forms to be in the same position when they are deposited on the forms which are already present on the table of the apparatus. Thus, the influence of the angle between the supply conveyor and the horizontal plane is eliminated in this way.
Known means can be present in the provided apparatus to bring the table on which a unit is present after formation by cutting off a fold, downwardly, to remove the severed stack unit from the table, and thereafter to return the table upwardly to its initial position.
There may also be provided in the apparatus a wall which is divided into two sections, and support means for the stack-opening finger and the hold-down means. The operating means for these are provided on a support construction which is movable in substantially the horizontal plane relative to said second vertical wall and in addition may be locked in certain positions. The provided apparatus is thus rendered suitable for use with sheets of various dimensions and which constitute the web of forms.
The flexibility of the provided apparatus is also assisted by replacing the table onto which the pile is deposited by another of corresponding size when the sheet size is changed. It is, however, possible that the table may comprise segments which are slidably movable relative to each other so as to form varying surface areas of desired dimensions.